Marker cartridge



FIG. 1 is a perspective view of a marker cartridge showing our new design;

FIG. 2 is a side view of the marker cartridge of FIG. 1;

FIG. 3 is a front view of the marker cartridge of FIG. 1; and,

FIG. 4 is a rear view of the marker cartridge of FIG. 1.

The broken lines represent portions of the marker cartridge that form no part of the claimed design. 

CLAIM We claim the ornamental design for a marker cartridge, as shown and described. 